U.S. Pat. No. 5,711,539 issued to the same inventor disclosed a magnetically-restored steerable roller skate. However, it has the following drawbacks:    1. Once the magnet 4b is damaged, it is difficult to dismantle the magnet from its holder (25f).    2. The aperture A between the first and second magnets 4a, 4b is fixed and not adjustable. For a big aperture as caused by poor quality control during the manufacturing, a magnetic attractive force between the two magnets will be weakened.    3. The magnet is formed as a slim rectangular shape, producing smaller magnetic force.
The present inventor has found the drawbacks of the prior art and invented the present roller skate with enhanced functions.